Abstract

We consider the future of the elm in the United Kingdom by analysing a simple model for the spread of Dutch elm disease. We show that this model, using biologically plausible parameterizations, is capable of mirroring observed data over short timescales such as a decade, but also demonstrates, over century-long timescales, a wide variety of outcomes ranging from pathogen extinction to substantial elm loss. This complexity of outcome from a simple model suggests that a greatly improved understanding of the basic population dynamics of elm and of the epidemiology of the causal fungus is necessary to analyse the future of the elm, the effect of spatial or genetic heterogeneity, or the impact of human interventions. We also use the model to discuss briefly the qualitative evolutionary impact of the combined saprophytic and parasitic stages of the fungal lifecycle.